Remove Cow around scalar buffers (#720)

Originally scalars were always references onto external buffers. Then in
#119 that was changed to try
to better support bindings that can't have lifetime references. (E.g.
neither python nor JS allow exports with lifetime references, because
they can't verify when data will still be valid in those environments).

But over time it turned out that we really needed fully separate structs
for these (e.g. `OwnedPoint`) that don't have their own lifetime
parameters. This means that we never actually needed to make `Point`
_itself_ owned. We need to have separate structs anyways for the
bindings.

Having Cow on the scalars only serves to make coordinate access slower,
because there's an indirection on access to the coordinate buffer.

### Change list

- Remove `Cow` wrappers on the internal buffers on scalars.

Closes #472

Closes #449

js/src/scalar/linestring.rs

@@ -4,9 +4,9 @@ use wasm_bindgen::prelude::*;
 #[wasm_bindgen]
 pub struct LineString(pub(crate) OwnedLineString<i32, 2>);
 
-impl<'a> From<LineString> for geoarrow::scalar::LineString<'a, i32, 2> {
-    fn from(value: LineString) -> Self {
-        value.0.into()
+impl<'a> From<&'a LineString> for geoarrow::scalar::LineString<'a, i32, 2> {
+    fn from(value: &'a LineString) -> Self {
+        (&value.0).into()
     }
 }
 

js/src/scalar/multilinestring.rs

@@ -4,9 +4,9 @@ use wasm_bindgen::prelude::*;
 #[wasm_bindgen]
 pub struct MultiLineString(pub(crate) OwnedMultiLineString<i32, 2>);
 
-impl<'a> From<MultiLineString> for geoarrow::scalar::MultiLineString<'a, i32, 2> {
-    fn from(value: MultiLineString) -> Self {
-        value.0.into()
+impl<'a> From<&'a MultiLineString> for geoarrow::scalar::MultiLineString<'a, i32, 2> {
+    fn from(value: &'a MultiLineString) -> Self {
+        (&value.0).into()
     }
 }
 

js/src/scalar/multipoint.rs

@@ -4,9 +4,9 @@ use wasm_bindgen::prelude::*;
 #[wasm_bindgen]
 pub struct MultiPoint(pub(crate) OwnedMultiPoint<i32, 2>);
 
-impl<'a> From<MultiPoint> for geoarrow::scalar::MultiPoint<'a, i32, 2> {
-    fn from(value: MultiPoint) -> Self {
-        value.0.into()
+impl<'a> From<&'a MultiPoint> for geoarrow::scalar::MultiPoint<'a, i32, 2> {
+    fn from(value: &'a MultiPoint) -> Self {
+        (&value.0).into()
     }
 }
 

js/src/scalar/multipolygon.rs

@@ -4,9 +4,9 @@ use wasm_bindgen::prelude::*;
 #[wasm_bindgen]
 pub struct MultiPolygon(pub(crate) OwnedMultiPolygon<i32, 2>);
 
-impl<'a> From<MultiPolygon> for geoarrow::scalar::MultiPolygon<'a, i32, 2> {
-    fn from(value: MultiPolygon) -> Self {
-        value.0.into()
+impl<'a> From<&'a MultiPolygon> for geoarrow::scalar::MultiPolygon<'a, i32, 2> {
+    fn from(value: &'a MultiPolygon) -> Self {
+        (&value.0).into()
     }
 }
 

js/src/scalar/point.rs

@@ -4,9 +4,9 @@ use wasm_bindgen::prelude::*;
 #[wasm_bindgen]
 pub struct Point(pub(crate) OwnedPoint<2>);
 
-impl<'a> From<Point> for geoarrow::scalar::Point<'a, 2> {
-    fn from(value: Point) -> Self {
-        value.0.into()
+impl<'a> From<&'a Point> for geoarrow::scalar::Point<'a, 2> {
+    fn from(value: &'a Point) -> Self {
+        (&value.0).into()
     }
 }
 

js/src/scalar/polygon.rs

@@ -4,9 +4,9 @@ use wasm_bindgen::prelude::*;
 #[wasm_bindgen]
 pub struct Polygon(pub(crate) OwnedPolygon<i32, 2>);
 
-impl<'a> From<Polygon> for geoarrow::scalar::Polygon<'a, i32, 2> {
-    fn from(value: Polygon) -> Self {
-        value.0.into()
+impl<'a> From<&'a Polygon> for geoarrow::scalar::Polygon<'a, i32, 2> {
+    fn from(value: &'a Polygon) -> Self {
+        (&value.0).into()
     }
 }
 

src/array/binary/array.rs

@@ -205,7 +205,7 @@ impl<'a, O: OffsetSizeTrait> GeometryArrayAccessor<'a> for WKBArray<O> {
     type ItemGeo = geo::Geometry;
 
     unsafe fn value_unchecked(&'a self, index: usize) -> Self::Item {
-        WKB::new_borrowed(&self.array, index)
+        WKB::new(&self.array, index)
     }
 }
 

src/array/linestring/array.rs

@@ -120,6 +120,10 @@ impl<O: OffsetSizeTrait, const D: usize> LineStringArray<O, D> {
         &self.coords
     }
 
+    pub fn into_inner(self) -> (CoordBuffer<D>, OffsetBuffer<O>, Option<NullBuffer>) {
+        (self.coords, self.geom_offsets, self.validity)
+    }
+
     pub fn geom_offsets(&self) -> &OffsetBuffer<O> {
         &self.geom_offsets
     }
@@ -288,7 +292,7 @@ impl<'a, O: OffsetSizeTrait, const D: usize> GeometryArrayAccessor<'a> for LineS
     type ItemGeo = geo::LineString;
 
     unsafe fn value_unchecked(&'a self, index: usize) -> Self::Item {
-        LineString::new_borrowed(&self.coords, &self.geom_offsets, index)
+        LineString::new(&self.coords, &self.geom_offsets, index)
     }
 }
 

src/array/multilinestring/array.rs

@@ -329,7 +329,7 @@ impl<'a, O: OffsetSizeTrait, const D: usize> GeometryArrayAccessor<'a>
     type ItemGeo = geo::MultiLineString;
 
     unsafe fn value_unchecked(&'a self, index: usize) -> Self::Item {
-        MultiLineString::new_borrowed(&self.coords, &self.geom_offsets, &self.ring_offsets, index)
+        MultiLineString::new(&self.coords, &self.geom_offsets, &self.ring_offsets, index)
     }
 }
 

src/array/multipoint/array.rs

@@ -119,6 +119,10 @@ impl<O: OffsetSizeTrait, const D: usize> MultiPointArray<O, D> {
         &self.coords
     }
 
+    pub fn into_inner(self) -> (CoordBuffer<D>, OffsetBuffer<O>, Option<NullBuffer>) {
+        (self.coords, self.geom_offsets, self.validity)
+    }
+
     pub fn geom_offsets(&self) -> &OffsetBuffer<O> {
         &self.geom_offsets
     }
@@ -278,7 +282,7 @@ impl<'a, O: OffsetSizeTrait, const D: usize> GeometryArrayAccessor<'a> for Multi
     type ItemGeo = geo::MultiPoint;
 
     unsafe fn value_unchecked(&'a self, index: usize) -> Self::Item {
-        MultiPoint::new_borrowed(&self.coords, &self.geom_offsets, index)
+        MultiPoint::new(&self.coords, &self.geom_offsets, index)
     }
 }
 

src/array/multipolygon/array.rs

@@ -180,6 +180,22 @@ impl<O: OffsetSizeTrait, const D: usize> MultiPolygonArray<O, D> {
         &self.coords
     }
 
+    pub fn into_inner(
+        self,
+    ) -> (
+        CoordBuffer<D>,
+        OffsetBuffer<O>,
+        OffsetBuffer<O>,
+        OffsetBuffer<O>,
+    ) {
+        (
+            self.coords,
+            self.geom_offsets,
+            self.polygon_offsets,
+            self.ring_offsets,
+        )
+    }
+
     pub fn geom_offsets(&self) -> &OffsetBuffer<O> {
         &self.geom_offsets
     }
@@ -375,7 +391,7 @@ impl<'a, O: OffsetSizeTrait, const D: usize> GeometryArrayAccessor<'a> for Multi
     type ItemGeo = geo::MultiPolygon;
 
     unsafe fn value_unchecked(&'a self, index: usize) -> Self::Item {
-        MultiPolygon::new_borrowed(
+        MultiPolygon::new(
             &self.coords,
             &self.geom_offsets,
             &self.polygon_offsets,

src/array/point/array.rs

@@ -222,7 +222,7 @@ impl<'a, const D: usize> GeometryArrayAccessor<'a> for PointArray<D> {
     type ItemGeo = geo::Point;
 
     unsafe fn value_unchecked(&'a self, index: usize) -> Self::Item {
-        Point::new_borrowed(&self.coords, index)
+        Point::new(&self.coords, index)
     }
 }
 

src/array/polygon/array.rs

@@ -326,7 +326,7 @@ impl<'a, O: OffsetSizeTrait, const D: usize> GeometryArrayAccessor<'a> for Polyg
     type ItemGeo = geo::Polygon;
 
     unsafe fn value_unchecked(&'a self, index: usize) -> Self::Item {
-        Polygon::new_borrowed(&self.coords, &self.geom_offsets, &self.ring_offsets, index)
+        Polygon::new(&self.coords, &self.geom_offsets, &self.ring_offsets, index)
     }
 }
 

src/array/rect/array.rs

@@ -173,7 +173,7 @@ impl<'a, const D: usize> GeometryArrayAccessor<'a> for RectArray<D> {
     type ItemGeo = geo::Rect;
 
     unsafe fn value_unchecked(&'a self, index: usize) -> Self::Item {
-        Rect::new_borrowed(&self.lower, &self.upper, index)
+        Rect::new(&self.lower, &self.upper, index)
     }
 }
 

src/io/geos/scalar/linestring.rs

@@ -24,7 +24,7 @@ impl<'a, O: OffsetSizeTrait, const D: usize> TryFrom<&'a LineString<'_, O, D>> f
     ) -> std::result::Result<geos::Geometry, geos::Error> {
         let (start, end) = value.geom_offsets.start_end(value.geom_index);
 
-        let sliced_coords = value.coords.clone().to_mut().slice(start, end - start);
+        let sliced_coords = value.coords.clone().slice(start, end - start);
 
         geos::Geometry::create_line_string(sliced_coords.try_into()?)
     }
@@ -34,7 +34,7 @@ impl<O: OffsetSizeTrait, const D: usize> LineString<'_, O, D> {
     pub fn to_geos_linear_ring(&self) -> std::result::Result<geos::Geometry, geos::Error> {
         let (start, end) = self.geom_offsets.start_end(self.geom_index);
 
-        let sliced_coords = self.coords.clone().to_mut().slice(start, end - start);
+        let sliced_coords = self.coords.clone().slice(start, end - start);
 
         geos::Geometry::create_linear_ring(sliced_coords.try_into()?)
     }

src/scalar/binary/owned.rs

@@ -14,15 +14,9 @@ impl<O: OffsetSizeTrait> OwnedWKB<O> {
     }
 }
 
-impl<'a, O: OffsetSizeTrait> From<OwnedWKB<O>> for WKB<'a, O> {
-    fn from(value: OwnedWKB<O>) -> Self {
-        Self::new_owned(value.arr, value.geom_index)
-    }
-}
-
 impl<'a, O: OffsetSizeTrait> From<&'a OwnedWKB<O>> for WKB<'a, O> {
     fn from(value: &'a OwnedWKB<O>) -> Self {
-        Self::new_borrowed(&value.arr, value.geom_index)
+        Self::new(&value.arr, value.geom_index)
     }
 }
 

src/scalar/binary/scalar.rs

@@ -3,38 +3,23 @@ use crate::trait_::GeometryScalarTrait;
 use arrow_array::{GenericBinaryArray, OffsetSizeTrait};
 use geo::BoundingRect;
 use rstar::{RTreeObject, AABB};
-use std::borrow::Cow;
 
 /// An Arrow equivalent of a Point
 #[derive(Debug, Clone)]
 pub struct WKB<'a, O: OffsetSizeTrait> {
-    pub(crate) arr: Cow<'a, GenericBinaryArray<O>>,
+    pub(crate) arr: &'a GenericBinaryArray<O>,
     pub(crate) geom_index: usize,
 }
 
 impl<'a, O: OffsetSizeTrait> WKB<'a, O> {
-    pub fn new(arr: Cow<'a, GenericBinaryArray<O>>, geom_index: usize) -> Self {
+    pub fn new(arr: &'a GenericBinaryArray<O>, geom_index: usize) -> Self {
         Self { arr, geom_index }
     }
 
-    pub fn new_borrowed(arr: &'a GenericBinaryArray<O>, geom_index: usize) -> Self {
-        Self {
-            arr: Cow::Borrowed(arr),
-            geom_index,
-        }
-    }
-
-    pub fn new_owned(arr: GenericBinaryArray<O>, geom_index: usize) -> Self {
-        Self {
-            arr: Cow::Owned(arr),
-            geom_index,
-        }
-    }
-
     pub fn into_owned_inner(self) -> (GenericBinaryArray<O>, usize) {
         // TODO: hard slice?
         // let owned = self.into_owned();
-        (self.arr.into_owned(), self.geom_index)
+        (self.arr.clone(), self.geom_index)
     }
 }
 

src/scalar/linestring/owned.rs

@@ -25,23 +25,17 @@ impl<O: OffsetSizeTrait, const D: usize> OwnedLineString<O, D> {
     }
 }
 
-impl<'a, O: OffsetSizeTrait, const D: usize> From<OwnedLineString<O, D>> for LineString<'a, O, D> {
-    fn from(value: OwnedLineString<O, D>) -> Self {
-        Self::new_owned(value.coords, value.geom_offsets, value.geom_index)
-    }
-}
-
 impl<'a, O: OffsetSizeTrait, const D: usize> From<&'a OwnedLineString<O, D>>
     for LineString<'a, O, D>
 {
     fn from(value: &'a OwnedLineString<O, D>) -> Self {
-        Self::new_borrowed(&value.coords, &value.geom_offsets, value.geom_index)
+        Self::new(&value.coords, &value.geom_offsets, value.geom_index)
     }
 }
 
 impl<O: OffsetSizeTrait> From<OwnedLineString<O, 2>> for geo::LineString {
     fn from(value: OwnedLineString<O, 2>) -> Self {
-        let geom = LineString::from(value);
+        let geom = LineString::from(&value);
         geom.into()
     }
 }

src/scalar/linestring/scalar.rs

@@ -9,15 +9,14 @@ use crate::trait_::{GeometryArraySelfMethods, GeometryScalarTrait};
 use arrow_array::OffsetSizeTrait;
 use arrow_buffer::OffsetBuffer;
 use rstar::{RTreeObject, AABB};
-use std::borrow::Cow;
 
 /// An Arrow equivalent of a LineString
 #[derive(Debug, Clone)]
 pub struct LineString<'a, O: OffsetSizeTrait, const D: usize> {
-    pub(crate) coords: Cow<'a, CoordBuffer<D>>,
+    pub(crate) coords: &'a CoordBuffer<D>,
 
     /// Offsets into the coordinate array where each geometry starts
-    pub(crate) geom_offsets: Cow<'a, OffsetBuffer<O>>,
+    pub(crate) geom_offsets: &'a OffsetBuffer<O>,
 
     pub(crate) geom_index: usize,
 
@@ -26,8 +25,8 @@ pub struct LineString<'a, O: OffsetSizeTrait, const D: usize> {
 
 impl<'a, O: OffsetSizeTrait, const D: usize> LineString<'a, O, D> {
     pub fn new(
-        coords: Cow<'a, CoordBuffer<D>>,
-        geom_offsets: Cow<'a, OffsetBuffer<O>>,
+        coords: &'a CoordBuffer<D>,
+        geom_offsets: &'a OffsetBuffer<O>,
         geom_index: usize,
     ) -> Self {
         let (start_offset, _) = geom_offsets.start_end(geom_index);
@@ -39,47 +38,16 @@ impl<'a, O: OffsetSizeTrait, const D: usize> LineString<'a, O, D> {
         }
     }
 
-    pub fn new_borrowed(
-        coords: &'a CoordBuffer<D>,
-        geom_offsets: &'a OffsetBuffer<O>,
-        geom_index: usize,
-    ) -> Self {
-        Self::new(
-            Cow::Borrowed(coords),
-            Cow::Borrowed(geom_offsets),
-            geom_index,
-        )
-    }
-
-    pub fn new_owned(
-        coords: CoordBuffer<D>,
-        geom_offsets: OffsetBuffer<O>,
-        geom_index: usize,
-    ) -> Self {
-        Self::new(Cow::Owned(coords), Cow::Owned(geom_offsets), geom_index)
-    }
-
-    /// Extracts the owned data.
-    ///
-    /// Clones the data if it is not already owned.
-    pub fn into_owned(self) -> Self {
+    pub fn into_owned_inner(self) -> (CoordBuffer<D>, OffsetBuffer<O>, usize) {
         let arr = LineStringArray::new(
-            self.coords.into_owned(),
-            self.geom_offsets.into_owned(),
+            self.coords.clone(),
+            self.geom_offsets.clone(),
             None,
             Default::default(),
         );
         let sliced_arr = arr.owned_slice(self.geom_index, 1);
-        Self::new_owned(sliced_arr.coords, sliced_arr.geom_offsets, 0)
-    }
-
-    pub fn into_owned_inner(self) -> (CoordBuffer<D>, OffsetBuffer<O>, usize) {
-        let owned = self.into_owned();
-        (
-            owned.coords.into_owned(),
-            owned.geom_offsets.into_owned(),
-            owned.geom_index,
-        )
+        let (coords, geom_offsets, _validity) = sliced_arr.into_inner();
+        (coords, geom_offsets, 0)
     }
 }
 
@@ -114,7 +82,7 @@ impl<'a, O: OffsetSizeTrait, const D: usize> LineStringTrait for LineString<'a,
     }
 
     unsafe fn coord_unchecked(&self, i: usize) -> Self::ItemType<'_> {
-        Point::new(self.coords.clone(), self.start_offset + i)
+        Point::new(self.coords, self.start_offset + i)
     }
 }
 
@@ -132,7 +100,7 @@ impl<'a, O: OffsetSizeTrait, const D: usize> LineStringTrait for &'a LineString<
     }
 
     unsafe fn coord_unchecked(&self, i: usize) -> Self::ItemType<'_> {
-        Point::new(self.coords.clone(), self.start_offset + i)
+        Point::new(self.coords, self.start_offset + i)
     }
 }